The present invention relates to an electrostatic powder coating apparatus used as a partial coating device for a workpiece such as an armature of a motor or the like and for curing a powder coat electrostatically adhered to the surface of the workpiece for coating.
A typical prior art coating system for partially coating a workpiece such as an armature of a motor or the like is shown in FIG. 19. Namely, the following units are arranged linearly in series: a heating and degreasing section a for heating and degreasing the workpiece; a first cooling section b for air cooling the workpiece that has been heated and degreased; a jig putting-in unit c for mounting a masking jig onto a non-coated portion of the workpiece; an electrostatic coater d for electrostatically coating a powder coat d that has been laid on the workpiece by air; a workpiece outer circumference cleaner e for removing an extra amount of powder resin coat adhered to the outer circumferential surface of the workpiece; a curing section f for heating and melting the powder coat adhered to a surface to be coated of the workpiece for fixation of the powder coat as a coating film after removal of the powder coat adhered to a masking jig by using a jet flow of air; a second cooling section g for cooling the workpiece that has been heated by the curing section f; and a jig putting-out unit h for removing the workpiece from the masking jig. The surface, to be coated, of the workpiece is coated in a process for delivering the workpiece in order from the heating and degreasing section a to the jig putting-out unit h.
The electrostatic coater d, the workpiece outer circumference cleaner e and the curing section f are covered by a single dust protecting cover i. The dust protecting cover i is connected by a dust collector to a powder coat collection section j through passages of pipes. Namely, the flown powder coat that has not been adhered to the workpiece in the electrostatic coater d or the extra powder coat that has been removed from the workpiece in the work outer circumference cleaner e or the powder coat that has been removed from the surface of the masking jig by an air injection means provided in the curing section f are floated within the dust protecting cover i and absorbed and collected by the powder coat collecting section j to be fed to the electrostatic coater d. Also, the masking jig that has been removed from the workpiece in the jig putting-out unit i is fed back to the jig putting-in unit c to be reused in the jig putting-in unit c.
However, according to the above-described prior art, it is pointed out that, due to the fact that the sections from the heating and degreasing section a to the jig putting-out unit h are arranged and disposed linearly in series and further due to the fact that the two cleaning sections (first and second cooling sections b and g) that need a relatively large volume for cooling the heated workpiece in the transfer process are arranged downstream of the heating and degreasing section a and downstream of the curing section f, the apparatus as a whole is long in length and a large working space is required. Also, since the dust protecting cover i covers the electrostatic coater d, the workpiece outer circumference cleaner e and the curing section f as a whole so that its volume is enlarged, the powder coat diffused in the space within the dust protecting cover i is not immediately absorbed or collected in the powder coat collecting section j but is likely to be adhered to the surface of the equipment contained in the dust protecting cover i or the inner surface of the dust protecting cover i or the like. It is therefore necessary to clean the interior of the dust protecting cover i at least once a week.